Credit

Caption

Mars losing its atmosphere. Artist's impression of the atmosphere eroded by the solar wind as a solar storm approaches. The solar wind is a stream of particles, mainly protons and electrons, flowing from the sun (right) at a speed of about one million miles per hour. The magnetic field carried by the solar wind as it flows past Mars (lower left) can generate an electric field which accelerates ions in Mars' upper atmosphere and shoots them into space. The loss of atmospheric gases increases during solar storms, where there are large eruptions of mass and energy from the sun's surface. Over time the continual erosion of the atmosphere has contributed to the change in the martian climate from warm and moist to cold and arid.